Horizontal boring machine



Oct. 7, 1969 T. R. MELSHEIMER ETAL 3,470,968

HORIZONTAL BORING MACHINE .5 Sheets-Sheet 1 Filed Sept. 12. 1967 IN VENTOR 750 P. MELSHE/MER, R/

CHA RD E MEL SHE/MER 5y Eon A20 D. O'BR/A/v 7 MER mum/foes 7E0 R. MELSHE/MEI? 5 Sheets-Sheet 2 R/cHA 120 F MELSHE/ EDWARD D. GER/AN T. R.MELSHEIMER ETAL HORIZONTAL BORING MACHINE VIIIIIIIIIIIA Oct. 7, 1969Filed Sept. 12, 1967 ATTORNEY Oct. 7, 1969 1; E H M ETAL 3,470,968

HORIZNTAL BORING MACHINE Filed Sept. 12, 1967 5 Sheets-Sheet 5 FIG. 4

mum/7025 72:0 R. M51. SHE/MEI? RICHARD FMELsHE/Mm ay fan/A20 D. OER/ANAwoe/vsy Get. 7, 1969 MELSHEMER ErAL 3,470,968

HORIZONTAL BORING MACHINE I Filed Spt. 12, 1967 s Sheets-{Sheet 4lNl/E/V 7025 7'50 R MEL SHE/MEIR,

R/CHARD FMELSHE/MER B EDWARD D. O'BR/AN ATTOEA/EY Oct. 7, 1969 MELSHEMERETAL 3,470,968

HORIZONTAL BORING MACHINE Filed Sept. 12. 1967 5 Sheets-Sheet 5lNl/EA/TOES f 750 R MELfi/YE/MER,

P/CHAED F. Mas/15mm? EDWARD D. O'BR/A/v A 77'02NEY United States Patent3,470,968 HORIZONTAL BORING MACHINE Ted R. Melsheimer, 1924 IsabellaAve., and Richard F. Melsheimer, 524 Almora, both of Monterey Park,Calif. 91754 Filed Sept. 12, 1967, Ser. No. 667,224 Int. Cl. E21c 11/02;E2111 19/00, 21/04 U.S. Cl. 173--24 2 Claims ABSTRACT OF THE DISCLOSUREThe horizontal drilling machine is particularly arranged for positioningon the ground surface and rotating and advancing a drill string. Thedrill pipe is sufficiently flexible to permit the pipe to enter adrilling pit and then proceed horizontally from the pit for drilling ahorizontal hole for later pipe insertion. For proper control of drillingthe horizontal drilling machine has hydraulically powered propulsionalong the ground surface, together with selectable one or two wheeldrive fixed to the drive axle. Furthermore, hydraulic power rotates thedrill string so that optimum control of drill rotation and drill advanceare both obtained. Water injection through the drill string is oftenhelpful in such drilling. In the present horizontal drilling machine, awater-oil heat exchanger is employed to cool the hydraulic oil used forthe propulsion and drill rotation. Furthermore, a water reservoir isemployed, which is filled from any conventional source. A float operatedvalve controls such filling. A separate water pump is provided, togetherwith pressure controls therefor, so that pressure of Water to the drillstring can be controlled for optimum water flow.

Background The horizontal boring machine of this invention lies in thoseclasses of machines which are arranged for boring horizontal holes inthe earth for the subsequent installation of pipes.

There are machines in the prior art which accomplish the samegeneralized purpose. The prior machines, however, require that the meansfor rotating the drill be located so that the drill can movehorizontally into an earth face in which the drilled hole is desired.For the most part, this requires the digging of a pit and the placementof at least the drill rotating structure, together with the drill stringin the pit. In some cases the advancement of the drill string isaccomplished from structure exteriorly of the pit, and in some cases theentire advancement and drill rotating structure must be located in thepit. This requires a relatively large pit, at least as long as thelength of the drilled hole. When a pipe is to be placed, this requiresthat at least half of the length of the installation must be dug intotrench or pit form. The net result is that such drilling is only usefulin drilling under short fixed obstructions, such as sidewalks anddriveways.

Summary The horizontal boring machine of this invention thus comprises apower unit which is placed upon the top of the ground surface. Thisboring unit has both a drill rotating unit thereon and a propulsive unitthereon for propelling the entire power unit along the ground, Both arehydraulic powered for the infinite control that such powering provides.The drill rotating unit is mounted at the front of the power unit and isarranged so that a moderately flexible drill string can be rotativelydriven thereby. This drill string is sufiiciently flexible that it canbend into a short trench, and thence horizontally out of the trench soas to drill a horizontal hole away from the trench. This permits arelatively long string of drill pipe and a relatively long horizontaldrilling accomplishment with a relatively short trench. Since the powerunit moves along the surface of the ground, the length of the trenchneed not be as great as the length of the drilling operation. Instead,long drilling can be accomplished employing only a short trench.Additionally, water cooling is provided for the hydraulic system. Thecooling employs the water which is injected through the drill string toaid in drilling. The power unit is an integrated structure which employsa hydraulic power supply with separate controls for drilling and fordrill advancing and a fully controlled water system for hydraulic oilcooling and for drilling.

It is thus an object of this invention to provide a horizontal boringmachine which provides fully controlled operation for optimum horizontalboring, including drill rotation and drill advance. It is another objectof this invention to provide a horizontal boring machine which comprisesa power unit including drill rotating structure which is supported uponand advanced along the ground for drilling of horizontal undergroundholes by means of an elongated drill string which enters the groundthrough a fairly short trench. It is another object of this invention toprovide a power unit which employs a Water system which discharges waterthrough the drill string for aid in drilling, the water system havingits own pump and reservoir to provide water under pressure at optimumconditions of pressure and flow, and which water is also used forcooling the hydraulic power supply which provides drill rotation andpower unit propulsion. It is another object of this invention to providea horizontal boring machine which has selective propulsion along theground, including a low speed for more diflicult boring operations withlarger boring bits, and a selectable higher speed for normal transitinto position, and which propulsion mechanism includes a driving axlewith a single wheel fixed thereto and with a second wheel selectivelyfixable thereto so that positive traction can be obtained with one ortwo ground engaging Wheels. It is a further object of this invention toprovide an economically constructed but fully controllable horizontalboring machine whereby boring can be controlled by one man. It isanother object of this invention to provide a horizontal boring machinewhich is economic of construction, convenient and easy to use and oflong life so as to readily and economically bore horizontal holes in theground. Other objects and advantages of this invention will becomeapparent from the following portion of this specification, the claimsand the attached drawings.

Description of the drawings FIG. 1 is a side elevational view of thehorizontal boring machine of this invention.

FIG. 2 is a top plan view thereof.

FIG. 3 is a front end elevational view thereof.

FIG. 4 is an enlarged top plan view, with parts broken away, showing thehorizontal propulsion mechanism 01 the boring machine.

FIG. 5 is an enlarged section taken generally along the line 5-5 of FIG.4.

FIG. 6 is an enlarged section taken generally along thr line 6-6 of FIG.4.

FIG. 7 is an enlarged section taken generally along tllt line 7-7 ofFIG. 4.

FIG. 8 is an enlarged side elevational View, with part: broken away,showing the stiff leg jack.

FIG. 9 is an enlarged section taken generally along the line 9-9 of FIG.8.

FIG. 10 is an enlarged vertical section taken througl the drill rotatinghead of the boring machine, generally along the line 10-10 of FIG. 3.

FIG. 11 is a schematic isometric view of the hydraulii circuit whichpowers the drill rotation on the boring machine.

FIG. 12 is a schematic isometric view of the hydraulic circuit whichpowers the advance of the boring machine. FIG. 13 is a schematicisometric view of the water circuit which cools the hydraulic oil andwhich supplies water under pressure to the drill head.

Description In FIGS. 1, 2 and 3, the horizontal boring machine of thisinvention is generally indicated at 10. It has a chassis 12 which servesas a structural means for supporting all of its parts, and serves as areservoir, as hereinafter described. Mounted upon the chassis is primemover 14 which serves as a prime power source for propulsion of thehorizontal boring machine along the ground surface and for power torotate the drill. Front wheels 16 and 18 are steerably mounted uponfront axle 20 which is mounted to the front of chassis 12 by means ofpivot 22. This pivot permits the front axle 20 to swing upon thelongitudinal axis of the boring machine to thus permit the boringmachine to equalize its weight upon all four wheels on uneven ground.Steering linkage 24 is connected to steering wheel 26 so that theoperator positioned adjacent the steering wheel can direct theorientation of the machine as it progresses.

The rear of boring machine 10 is supported upon its drive wheels 28 and30. The drive wheels, in turn, are mounted upon axle 32 which isrotatably mounted with respect to the rear of chassis 12. Hub 34 isfixed to axle 32 so that positive drive is obtained when the axlerotates. Brake drum 36 is fixed to axle 32. Brake drum 36 is in the formof a V belt pulley, and brake band 38 extends around the brake drum, seeFIG. 7. One end of brake band 38 is fixed by link 40 to frame 42 whichforms part of the chassis. Brake lever 44 is also pivoted to frame 42and is urged upward by means of spring 46. The other end of brake band38 is secured to brake lever 44 by means of link 48. Operation of brakelever 44 by having the operator press his foot thereon causes tighteningof the brake band about the brake drum 36 to lock rotation of axle 32and stop motion of the boring machine 10.

As is seen in FIGS. 4 and 5, outboard of sprockets 50 and 52, which arefixed to axle 32, drive wheel 30 is mounted upon axle 32. Drive wheel 30is mounted upon hub 54 which in turn is mounted upon bearing housing 56.Bearings 58 and 60 are mounted between axle 32 and bearing housing 56 sothat hub 54 is freely rotatably mounted upon axle 32. By thisconstruction, the horizontal boring machine 10 can turn corners withoutdragging a drive wheel. Furthermore, since drive wheel 28 is fixed tothe axle, normal propulsion on firm surfaces is obtained so that this issufficient for many horizontal boring jobs. However, in those caseswhere the ground surface is soft and traction is poor, it is desirableto irrotatably fix hub 54 upon axle 32. Spline 62 is integrally formedon the end of axle 32 and extends out of bearing housing 56. A cap orlocking hub 64 has a spline opening therein to receive spline 62 and isarranged to be bolted upon the end of bearing housing 56 to thusirrotatably fix the bearing housing and hub 54 with respect to axle 32.When fixed in this manner, drive wheel 30 also serves as a groundengaging propulsion wheel. Instead of a plain cap 64, a commercialcoupling can be used.

In order to aid in the installation of cap or locking hub 64 it isdesirable to raise the wheel 30 off the ground so that it can be rotatedfor alignment of the engagement splines within the cap or locking hub 64and alignment of the bolt holes in the cap with the corresponding holesin the bearing housing 56. This is accomplished by means of stiff legjack 66.

As is seen in FIGS. 8 and 9, stiff leg jack 66 comprises leg 68 which ispivoted upon pivot 70 which is secured 4 to bracket 72. Bracket 72includes stop 74 which limits the rotative travel of leg 68 in theclockwise direction. Additionally, opening 76 is positioned on leg 68for the reception of stop pin 78 which can be engaged in opening 76 torestrain leg 68 in a position where it is clear to the ground, as isillustrated in FIG. 1. Stop pin 78 is spring urged towards engagementwithin opening 76 and can be held out of engagement by means of atransverse pin (not shown) across stop pin 78 which can be selectivelyengaged in a corresponding slot in bracket 72.

When it is desired that wheel 30 be raised for the purpose of locking itto axle 32, stop pin 78 is disengaged from its opening 76 and leg 68 ispermitted to rest upon the ground or other supporting surface. When theboring machine 10 is driven forward by means of coupled wheel 28 and asit moves forward, the portion of the boring machine adjacent the jackleg 66 is raised to raise wheel 20 off of the ground. The wheel can thenbe freely rotated for locking the coupling or placing cap 64 in place.

Referring to FIG. 4, motor 80 is a hydraulic motor powered from ahydraulic source hereinafter described. Motor 80 is connected to drivereduction gear box 82 which has output sprocket 84 connected to itsoutput shaft. Chain 86 engages upon sprocket 84 and upon sprocket 88which is mounted on counter shaft 90. Counter shaft 90 is suitablyrotatably mounted upon the chassis 12. Sprockets 92 and 94 are rotatablymounted upon the counter shaft and are respectively connected by chains96 and 98 to drive sprockets 50 and 52. Clutch 100 is mounted to rotatewith the shaft on the square portion of the shaft illustrated in FIG. 6.The clutch 100 has four round pins 101 which protrude from its side.These pins 101 engage mating faces upon the facing sides of thesprockets 92 and 94. Thus, by shifting the clutch 100, drive from themotor to axle 32 is selectable through chain 96 or chain 98. Due to thefact that sprockets 92 and 94 are different size, different speed ratiosare obtained. Yoke 102 engages clutch 100 to move it from one engagementto the other. Handle 104, see FIGS. 1, 2 and 3, is accessible to theoperator of the boring machine to permit him to select this ratio.

As is seen in FIGS. 1, 2 and 3, prime mover 14 is an internal combustionengine 106 which is directly connected to drive hydraulic pump 108. Pump110 is a water pump connected by suitable pulleys and belt 112 so thatit is also driven by engine 106. The fluid connections of these pumpswill be later described.

As is seen in FIGS. 1, 2 and 3, support arms 114 and 116 areupstandingly mounted on the front of chassis 12. They carry alignedpivot bearings adjacent their tops, which pivot bearings define a raisedtransverse pivot axis. Mounted on this pivot axis is drill driver 118.Drill driver 118 comprises a housing 120, see FIG. 10, from whichaligned trunnions 121 laterally extend. These aligned trunnions 121 aremounted in the pivot bearing 123 in the support arms so that the drilldriver can swing upon that horizontal axis.

Hydraulic motor 122 is flange mounted on the rear of housing 120. Theconnections of hydraulic motor 122 will be later described. Hydraulicmotor 122 has an output shaft which extends through the housing and ispreferably supported by a bearing on the front wall of housing 120. Theoutput shaft to motor 122 is indicated at 124. Shaft 124 carries piniongear 126. Idler shaft 128 is rotatably mounted on bearings in the frontand rear walls of housing 120. Idler shaft carries gear 130, fixedthereto, which is in gear tooth mesh with pinion gear 126. Furthermore,idler shaft carries fixed thereto drive sprocket 132 which thus rotateswith motor rotation. Drill shaft 134 extends through housing 120 and isrotatably mounted with respect thereto on bearings 136 and 138. Sprocket140 is fixed on drill shaft 134, between its bearings, and chain 142interconnects sprockets 132 and 140. The pinion gear 126 and geartogether with sprockets 132 and act as a speed reduction so that drillshaft 134 rotates at a slower speed than motor shaft 124.

Instead of using sprockets and chain in this speed reduction mechanism,gears alone could be used. Changes in the reduction ratio can beobtained to aid in changes in the speed ratio by changing the gears 126and 130. The cover 144 and the caps on bearings 136 and 138 are easilyremovable. Changes in ratio are rarely needed, but one ratio issatisfactory for nearly all of the boring that a particular boringmachine will be employed to perform. Thus, a quick change gear box isnot necessary, particularly in view of the variable speed capability ofhydraulic motor 122. Housing 120 is preferably totally closed, whencover 144 is in place, so that it can contain oil for lubrication of thegears, chain and bearings.

Drill shaft 134 has a passage 146 therethrough. At the rear of drillshaft 134, union tube 148 is rotatably fitted. Union tube 148 provides arotating joint of such nature that the union tube can remain stationarywhile shaft 134 rotates. The front end of shaft 134 carries threads andupon these threads are mounted adaptor 150. Adaptor 150 in turn isarranged to be threaded into the end of a string of drill pipe 152. Thedrill pipe string 152 can be assembled to be as long as needed for thejob, by screwing lengths of drill pipe together. The outer end of thedrill pipe string carries the drilling bit which actually performs thedrilling operation. Adaptor 152 is provided to permit the readyattachment of different sizes and styles of drill pipe 152 onto the endof shaft 134. Furthermore, the use of the adaptor protects the threadson the end of shaft 132 from excessive wear. Adaptor .150 and drill pipestring 152 are tubular so that water can be conveyed to the drilling biton the outer end of the drill pipe string.

In order to restrain adaptor 150 from rotation so that the drill pipestring 152 can be unscrewed therefrom, when it is necessary to makechanges in the drill pipe string, lock 154 is provided. Base plate 156is secured to the bottom of housing 120 and extends forward to supportlock tube 158. Lock arm 160 is slidably mounted in tube 158 and isbifurcated at its upper end to provide jaws 162 and 164, see FIG. 3.Flats 166 are provided on the exterior of adaptor 150 so that when lockarm 160 and its jaws are moved upwardly, the jaws engage around theflats 166 to thus prevent the adaptor from rotating. In this conditionthe drill pipe can be removed or otherwise acted upon. Furthermore, theadaptor can be easily unscrewed from the drill shaft by using this lockand rotating the motor in the reverse direction.

Referring to FIGS. 11 and 12, it is seen that the chassis 12 iscomprised of rectangular reservoirs 168 and 170. Reservoir 168 is awater reservoir while reservoir 170 is a hydraulic reservoir. Pump 108draws oil from the reservoir through suction line 172 and discharges itinto pressure line 174. The pump .108 is preferably a variable volumepressure compensated pump which can be preset to pump the requiredvolume of hydraulic fluid at a desired pressure. A pump case drainreturns internal leakage from this pump 108 back to oil reservoir 170.Pressure line 174 is connected to manifold 178 which supplies severalhydraulic needs.

In FIG. 11, line 180 receives hydraulic fluid under pressure frommanifold 178 and delivers it to reversing valve 182. Valve 182 has amanually operable handle 184, see FIGS. 1 and 2, for control of thespool in the valve. Motor lines 186 and 188 are connected between valve182 and motor 122 and are arranged so that upon shifting of the spool invalve 182, fluid under pressure is delivered through one of these motorlines while the other is connected to exhaust back into the reservoir.The pressure and exhaust functions of these lines can be reversed byvalve 182 to cause reversal of motor 122. Motor 122 also has a casedrain 190 which drains internal motor leakage back to the reservoir 170.The returning hydraulic fluid from motor 122, through valve 182, passes6 through exhaust line 192. Exhaust line 192 discharges to oil cooler194 which is attached to the side of reservoir 170 and has an externalconnection discharging the oil from the cooler into the reservoir 170.By this means the stopping and reversing of motor 122 is accomplished.

Referring to FIG. 12, the pump 108, pressure line 174 and pressure fluidmanifold 178 are again seen. Pressure gauge 196 is connected to themanifold to indicate to the operator the amount of hydraulic fluidpressure available to motors and 122. Bypass valve 198 is connected byline 200 to the manifold 178 and discharges to exhaust line 192. Thecontrol of flow through valve 198 controls the pressure in manifold 178by bypassing oil back to the reservoir. Thus, by manual control of thisvalve, the amount of fluid pressure available to both the motors iscontrolled.

A needle type valve 202 is connected by line 204 to the manifold 178 andis connected by line 206 to manually operable reversing valve 208.Handle 110, see FIG. 2, is at the operators position so that theoperator can conveniently manually control valve 208. Motor lines 212and 214 are connected between the valve 208 and motor 80. Valve 208 isarranged so that the position of handle 210 directs hydraulic fluidunder pressure into lines 212 or line 214, while connecting the otherline to exhaust. Exhaust line 216 is connected between valve 208 andexhaust line 192 to handle this exhaust flow. Additionally, motor casedrain line 217 is connected from the case of motor 80 to reservoir 170to drain internal leakage from the motor back into the sump.

The reservoirs 168 and 170 are also illustrated in FIG. 13, wherein thewater system is described. Connection is provided at 218 for anyconvenient source of water under pressure. Preferably a hose from a citywater supply or the like is connected at 218. Valve 220 is a shut offvalve which permits the water to flow into line 222. Valve 224 isoperated by float 226 which is positioned inside of reservoir 168 andthe float and valve act to maintain a constant level of water withinreservoir 168. Line 228 connects the discharge from valve 224 to oilcooler 194. Water and oil are prevented from mixing in oil cooler 194 byshell and tube construction or the like. Line 230 directs the water fromthe oil cooler into reservoir 168. Air vent 232 permits air to flow inand out of the reservoir in accordance with the changes in level ofwater therein.

Suction line 234 extends to the bottom of the reservoir and serves as apump suction line. Pump suction line 235 is connected to the inlet ofpump 110. Filter 236 protects the pump against contaminents in thereservoir. Water is discharged under pressure from pump 210 intopressure line 236. Pressure line 236 is connected to line 238 which hasboth a relief valve 240 and an orifice connected in parallel to exhaustline 244. The flow from both of these devices returns to reservoir 168through exhaust line 244. By this means, the pump 110 is protectedagainst over pressure and a certain minimum flow is always permittedthrough orifice 242 to prevent air lock of the pump. The main dischargefrom pressure line 236 goes through line 246 which carries pressuregauge 248 thereon. Additionally, line 246 extends to manually operablecontrol valve 250 which controls the water flow from line 246 to line252. Line 252 is at least partly flexible and is connected on its outerend to union tube 148. By this means the pressure and flow of water tothe drill bit is controlled to discharge the optimum amount of water forbest drilling.

In operation, when a hole is to be bored horizontally under the surfaceof level ground, a pit is dug to slightly more than the desired depth ofthe desired hole. The length of this pit depends on the flexibility ofthe drill pipe string 152. A fairly flexible drill pipe string can beused in most cases. The outer end of the drill pipe string carrying thedrill bit, is aligned in the bottom of this pit so that drilling willproceed in the proper direction. Thereupon, after starting the engine106, drilling proceeds. Motor 122 is started by operation of handle 184.Water is started by opening valves 220 and 250, with valve 250 beingopened to the extent necessary to provide a proper Water volume.Thereupon, valve 208 is operated by handle 210 so that the boringmachine 10 proceeds forward to push the string of drill pipe ahead ofit. The rotary speed of the drill head (or drill driver) is controlledby varying the throttle setting on the engine; in other Words, therotary speed of the driver is proportional to the volume of oildelivered which in turn is determined by the r.p.m. of the engine andpump. The by-pass valve 198 is used as a throttling valve only underconditions demanding exact control of direction or rotary speed.

As drilling proceeds as described in the preceding the gauge 196 can beused as an instrument by an operator in determining proper operation ofthe complete machine 10. In general it has been found that boringoperations can be most effeciently performed within a range of pressuresas shown by this gauge 196 which is lower than a range of pressures asshown by this gauge 196 which has proved to be most efiicient forreaming. A relatively constant pressure as shown by this gauge 196 canbe maintained by opening and/or closing the bypass valve 198. This isconsidered to be quite important.

If a larger hole is desired, a reamer is placed on the end of the drillstring, and while the drill string is being withdrawn, the hole isenlarged. At the same time, either a pipe pulling cable or the pipeitself can be pulled through the hole while the drill string is beingwithdrawn. When drilling is to be accomplished in relatively soft groundwheel 30 is locked to the axle by means of cap 64. This is accomplishedby raising wheel 30 on stitf leg jack '66 and locking the hub r cap 64so the wheel is fixed. Thereupon, the boring machine is driven off thejack 66 and the boring machine is propelled by having both drive wheelsfixed to the shaft.

We claim:

1. In a horizontal boring machine, said horizontal boring machinecomprising:

a chassis,

wheels on said chassis for supporting and propelling said chassis alongthe ground,

a hydraulic reservoir mounted on said chassis,

power means mounted on said chassis,

a hydraulic pump connected to said power means and connected to saidreservoir to draw hydraulic fluid from said reservoir and discharge itunder pressure,

the improvement comprising:

a boring string supported on said chassis so as to extend therefrom,

a drill motor mounted on said chassis, said drill motor being arrangedto be connected to a boring string for rotation of the boring string,said drill motor being connected to said hydraulic pump for poweringthereby,

a propulsion motor on said chassis, said propulsion motor beingconnected to at least one of said wheels so that rotation of saidpropulsion motor propels said chassis along the ground, said propulsionmotor being connected to said hydraulic pump to be powered thereby,

a water reservoir is mounted upon said chassis,

a water pump is connected to said power means to to driven thereby, saidwater pump being connected to draw water from said water reservoir andto discharge it through the drill string,

a heat exchanger is mounted upon said chassis,

said heat exchanger being connected to said water reservoir and to saidoil reservoir so that water cools the oil.

2. The horizontal boring machine of claim 1 including:

a float mounted in said water reservoir,

a water inlet valve connected to said reservoir and connected to saidfloat to be controlled thereby and arranged so that said float shuts offsaid Water inlet valve to prevent overfilling of said water reservoir, aheat exchanger connected to the Water outlet of said water inlet valvebeing said heat exchanger being connected so as to discharge water intosaid water reservoir so that Water passing through said water inletvalve passes through said heat exchanger and thence into said waterreservoir.

References Cited UNITED STATES PATENTS 2,656,152 10/1953 Moon 173-272,807,441 9/1957 Sewell 17327 2,985,250 5/1961 Goodrich et a1. 17327 X3,291,225 12/1966 Foran 173-164 ERNEST R. PURSER, Primary Examiner US.Cl. X.R.

@335 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,470 .968 Dated October 7, 1959 Inventor) Ted R. Melsheimer and RichardF. Melsheimer 7 It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 6 line 19 "l 10' should read --2l0--; column 6 line 48, 235"should read --234--; column 6 line 39 P236" should read --235--; Column6, line 51, 210' should read --l l0--; column 6 line 53 "ori f1 ce"should read "orifice 242".

SIGNED Auu SEALED JAN 204970 Attest:

Edward M. Fletcher, Ir.

WILLIAM E. 50mm, .13. Atteating Offxcer Gamiasioner of Patents

